Astronauts are trying to fix an essential part of equipment that can convert urine and sweat into drinkable water for them. This water recycling equipment, which costs $154 million, would make it possible for NASA to increase the crew aboard the ISS to six members.

Mission control have already asked station commander Michael Fincke on Sunday to remove the way the centrifuge is mounted on the water recycling system. During the past couple of days, the astronauts worked to fix the water recycling system so they could sent samples of water to Earth for analysis, but the system’s processor only operates for about two hours at a time and then shuts down.

While working to fix the problem, engineers are also studying whether there is possible to increase the number of crew members aboard the space station with the water recycling system working for only two hours at a time, said lead flight director Ginger Kerrick.

"If this is as good as it's going to get, we do need to be able to answer that question," Kerrick added.

The mission management decided not to extend the mission by an extra day because the astronauts have obtained enough water samples. The Endeavour will undock from the space station on Thanksgiving Day, according to the current schedule.

Meanwhile, Endeavour’s seven astronauts had a lot of work to do. They carried out three space walks, out of four scheduled. Astronauts Heide Stefanyshyn-Piper and Stephen Bowen cleaned and lubed a jammed joint of the station. The cleaning of the joint, which allows the station’s solar wings to change position so they can catch solar power, took the two astronauts about seven hours. Stefanyshyn-Piper lost a $100,000 tool kit in the process.